Printing screen coating apparatus

ABSTRACT

An apparatus and method for the automatic and controlled application of smooth, even, controlled thickness coatings of viscous fluids such as photographic emulsions to taut, flexible, suspended layers of materials such as silk printing screens. The apparatus employs an adjustable frame for supporting various sizes of materials to be coated in unique cooperation with special spreading means for evenly spreading viscous fluids on the screen as motive power means moves the spreading means at a controlled, predetermined rate. Preferably, curing means is supplied for drying or baking the fluid on the screen. The spreading means includes a tray for holding and spreading the fluid and a base for movably supporting the tray over the screen to be coated without direct, physical contact therewith. The tray moves in unison with the base by a unique arrangement employing magnetic attraction.

United States Patent 1191 Black PRINTINGSCREEN COATING APPARATUS [76] Inventor: James A. Black, 13700 Sparta N.

W., Kent City, Mich. 49330 22 Filed: June 1, 1972 21 Appl. No.: 258,856

52 U.S.C1 ..118/323,117/34,118/120,

118/325 51 1m. (:1. B05c 5/02 53 Field o f Search 118/100, 120, 123, 241,

REFERENCE 1111 3,834,348 Sept. 10, 1974 Primary Examiner-Mervin Stein Attorney, Agent, or Firm-Price, Heneveld, Huizenga & Cooper [5 7] ABSTRACT An apparatus and method for the automatic and controlled application of smooth, even, controlled thickness coatings of viscous fluids such as photographic emulsions to taut, flexible, suspended layers of materials such as silk printing screens. The apparatus employs an adjustable frame for supporting various sizes of materials to be coated in unique cooperation with special spreading means for evenly spreading viscous fluids on the screen as motive power means moves the spreading means at a controlled, predetermined rate. Preferably, curing means is supplied for drying or baking the fluid on the screen. The spreading means includes a tray for holding and spreading the fluid and a base for movably supporting the tray over the screen to be coated without direct, physical contact therewith. The tray moves in unison with the base by a unique arrangement employing magnetic attraction.

36 Claims, 9 Drawing Figures POSITION T 'Posmou PAIENTEU SEPI 01924 sum 1 or 3 SHEET 2 OF 3 PATENIEUSEP 1 01974 ELECTRICAL souaca PAIENTED SEP 1 0 I974 SHEH BM 3 REFERENCE PosmoN FIG. 4

REFERENCE REFERENCE UNE A \55 FIG. 8

PRINTING SCREEN COATING APPARATUS This invention relates to apparatus for automatic and controlled application of an even coating of a viscous fluid to a suspended layer of material and, more particularly, to apparatus for theapplication of emulsions and the like to printing screens and other taut, flexible, suspended layers of material in an automatic and controlled manner. I

BACKGROUND OF THE INVENTION It is well known that the preparation of photo-stencils for the printing industry requires a prepared light sensitive printing screen. Typically, the preparation of such screens requires the spreading of a photographic emulsion in the form of a viscous fluid over the surface of a printing screen stretched and suspended on one face of a supporting framework. After the screen is coated with the emulsion, the coating may be cured or dried. The screen is then ready for exposure to light while adjacent the desired negative such that the photostencil with a selected printing pattern results.

In the past, spreading the emulsion on the printing screen was done manually. The manual method generally utilized a channel or trough having a V-shaped cross section filled with the emulsion and manually drawn vertically upwardly over the surface of a printing screen that was in an upright position. The emulsion was allowed to flow over one edge of the V-shaped channel, and that same edge was used to wipe or spread the emulsion over the surface of the screen as the channel was drawn vertically upwardly. It is known that this manual method of coating printing screens is not fully satisfactory. Specifically, it is difficult to control the rate at which the fluid or emulsion runs out of the channel or trough. Additionally, it is difficult to control the pressure uniformly between the entire length of the trough and the screen to cause the emulsion to be evenly applied across the entire length of the channel. Finally, it is difficult if not impossible to maintain uniform emulsion thickness, especially the precise thickness required for high quality photostencils. In fact, only after a considerable time does a person acquire the skill necessary to effect a reasonable emulsion coating by the conventional technique. Even then, it is practically impossible to get the same thickness coating repeatedly.

SUMMARY OF THE INVENTION Accordingly, it is an object and feature of the present invention to provide an apparatus for the application of smooth, even coatings of viscous fluids, such as photographic emulsions and the like in controlled and predetermined thicknesses to suspended, taut, flexible layers of material such as a printing screen.

It is another object and feature of the present invention to provide an apparatus to apply controlled and predetermined thicknesses of viscous fluid on varying sizes of suspended, taut, flexible layers of material without requiring special manual dexterity and skill.

It is a further object and feature of the present invention to provide an apparatus for the application of viscous fluids to suspended, taut, flexible layers of printing screen and adaptable to apply these coatings to either side of the screen, i.e., whether the support frame is upright or inverted.

It is yet another object and feature of the present invention to provide an apparatus for the application of controlled coatings of viscous fluid to suspended layers of material in combination with adjacent facilities for curing the coating.

It is still another object and feature of the present invention to provide a method for coating suspended, taut, flexible layers of material such as a printing screen with viscous fluid such as photographic emulsion in an automatic and controlled manner.

These and other objects and features of the present invention are accomplished by a unique coating apparatus and method having in combination an adjustable support means for supporting a suspended layer of material such as a printing screen to be coated, an adjustable spreading means for holding a quantity of viscous fluid and automatically spreading controlled amounts of viscous fluid evenly on the layer of material, and special cooperative means for moving the spreading means along the layer.

The adjustable spreading means incorporates an elongated tray for theviscous fluid and a base for movably supporting the tray. The tray has apertures through which the viscous fluid flows and an adjustable closure means for controlling the rate of flow through the apertures. The base has two adjustable tray supports supporting an alignment rod for aligning the layer of material with the tray and two pairs of support wheels. The tray also has two pairs of wheels which cooperate with the alignment rod and the support wheels of the base'to support the tray over the screen which is positioned between the tray and base. The base and tray have cooperative magnetic retention means therebetween.

-Motive power means automatically and controllably moves the spreading means. Additionally, the apparatus may include a curing means for supporting the coating apparatus and for heating or drying the fluids applied with the coating apparatus to the layers of material.

These and other objects, advantages and features of the invention will become apparent from a study of the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the coating apparatus supporting a printing screen to be coated;

FIG. 2 is a perspective view of the apparatus in FIG. 1, but having the printing screen and tray means removed while showing a coated printing screen supported and partially withdrawn from the underlying curing means;

FIG. 3 is an exploded, fragmentary, perspective view of the adjustable spreading means;

FIG. 4 is a fragmentary end elevation of the spreading means shown in FIG. 3;

FIG. 5 is a fragmentary side elevation of one end of the spreading means shown in FIGS. 3 and 4;

FIG. 6 is a fragmentary plan view of the end portion of the spreading means shown in FIGS. 3, 4 and 5;

FIG. 7 is a schematic drawing of the motive power measn for the adjustable spreading means including the electrical control circuitry therefor;

. FIG. 8 is a fragmentary front elevation of a portion of the spreading means including the coating thickness control means; and

FIG. 9 is a fragmentary, cross-sectional view of the apparatus shown in FIG. 8 taken along line lX-IX of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT pared for use in the printing industry.

As shown in FIG. 1, the coating apparatus 10 generally comprises an adjustable support means 14 for supporting a suspended layer of screen material 16 to be coated. The suspended screen 16 is tautly stretched over and supported by a peripheral framework 18.

The viscous fluid or emulsion 24 can be spread over the upper surface of printing screen 16 whileso held,

by an adjustable spreading means 20 for holding a quantity of the viscous fluid and automatically spreading controlled amounts of the viscous fluid evenly-on the printing screen surface. Additionally, the coating apparatus 10 includes means 22 for moving the spreading means 20 along and over the printing screen 16 in a controlled manner at a predetermined rate.

Referring now to FIGS. 1 and 2, the adjustable support means 14 will be described vin greater detail. As shown therein, support means 14 comprises an adjustable frame for supporting framework such as that shown at 18. The frame 30 has a generally rectangular frame base 32 with three frame base members 34, 36 and 38 defining three sides of a rectangle. The fourth side of the rectangle or square is formed by housing 40 enclosing the means 20 for moving spreading means. A fourth frame base member 42 is spaced vertically from the level of the other three frame base members and provides asupport surface for the adjustable side members or rails 44 and 46. The frame base 32 is disposed horizontally and supported by means of brackets 48 and 50 and housing 40 from a horizontal supporting surface 13. In the preferred embodiment, the horizontal supporting surface 13 comprises the top of curing means 12 which, when used in combination with the coating apparatus 10, provides a conveniently located means for drying or curing the viscous fluid or emulsion 24 which has been spread on the layer of material or printing screen 16.

In the preferred embodiment, the support means 14 includes two adjustable side members or rails 44 and 46, although the use of only one adjustable side memher or rail is conceivable. Rails 44 and 46 are supported horizontally and are vertically spaced from the level of the frame base 32 by means of channels 52 and 54 and brackets 56 and 58. The rails 44 and 46 are movable I The framework 18 is secured to adjustable rails 44 and 46 by clamping means 60. The clamping means 60 include cantilevered bars 62 for engaging the edges of the framework 18. The cantilevered bars 62 are biased vertically downwardly by a spring biased rod 64 mounted in a retaining bearing block 66. The clamping means 60 are adjustable along the length of the rails 44 and 46 in slots 68 formed in the outside vertical side of each rail 44 and 46. The bearing block 66 is thus mounted within the slots 68 and is slidable therealong. Therefore, it will be understood that the adjustable support means 14 allows the side rails 44 and 46 to be adjusted along and between frame base members 36 and 38 to accommodate various sized frameworks 18. The clamping means 60 may then be used to securely fasten the framework 18 on rails 44 and 46 such that the spreading means 20 is centered therebetween and in position to spread a layer of viscous fluid or emulsion 24 on thesupported printing screen 16.

Also shown in FIGS. 1 and 2 is curing means 12. It forms va rectangular housing 70 having a closure means 72 hinged along line 74 to allow entry to the interior of housing 70. Mounted within housing 70 are means 76 for supporting frameworks 18 after a layer of viscous fluid or emulsion 24 has been applied thereto. The means for supporting the frameworks 18 comprise at least one adjustable rack '76 which may be adjusted to accommodate various sized frameworks 18. Rack 76 includes channels 78 and support rails 79 (F IG. 2) which slide along opposing side members of rack 76. Channels 78 include bearing surfaces (not shown) to facilitate the adjustment; Rack 76 is also rollably or slidably mounted within the housing 70 and is extendable outside the housing to facilitate placing framework 18 thereon. After the framework 18 has been placed on rack 76 it may then be rolled back into housing 70 and closure 72 then closed in preparation for the curing, drying or baking process. The curing process is controlled by a means for controlling the atmospheric conditions within the housing (not shown). This-means comprises a thermostatic control and ventilation means for controlling both the heat and the humidity within housing 70. Thus, the housing 70 is an insulated, airtight structure which may be used to heat, dry, or bake coated layers of material 16 which have been coated by apparatus 10.

Referring now to FIGS. 3 through 6 in addition to FIGS. 1 and 2, the unique spreading means 20 for coating the layers of suspended material with viscous fluids or emulsions will be described in greater detail. As shown in FIGS. 1 and 2, the adjustable spreading means comprises a spreading member tray means 80 (FIG. 1) and a supporting member base means 82 (FIG. 2). The tray means 80 includes an elongated tray 84 supported over the printing screen 16 by means of end supports 86 and 88. The base means 82 is disposed generally under the printing screen 16 and supports the tray means 80 by means of a pair of tray supports 90 and 92 adjustably mounted on a support bar 94 and including an alignment rod 96 rotationally mounted between tray supports 90 and 92. Generally then, the spreading means 20 has two main sections comprising the tray means 80 and thebase means 82. The tray means 80 is supported generally over the printing screen 16 by the base means 82 which is adjustably mounted below the printing screen. The printing screen 16 thus separates and vertically spaces tray means 80 and base means 82 apart by its thickness.

Referring now to FIG. 3, the structure and arrangement of the spreading means will be more fully understood. As depicted therein, tray means 80 includes an elongated tray 84 having a U-shaped cross section which is supported by end supports 86 and 88 at an angle with the horizontal, i.e., tilted toward one elongated edge. The exploded view FIG. 3 shows only the end support 86. End support 86 includes a U-shaped slot 98 formed on the interior side of support 86, which slot 98 receives the end of the U-shaped elongated tray 84. Tray 84 also includes a plurality of elongated slots 100 formed adjacent the elongated corner of the tray 84 which is closest to the printing screen 16 when the tray is supported in place. Thus, the viscous fluid or emulsion 24 may be poured into tray 84 and would normally flow out of apertures 100 across the width of the screen except for an adjustable closure means 102 which is pivotally mounted on end supports 86 and 88. Closure means 102 includes a door 104 supported between end members 106 by means of a support member 108 and fastening means such as screws 110. The end members 106 each include a pivot pin 112 which extend inwardly toward one another from end member 106. Pivot pins 112 correspond and cooperate with L- shaped slots 114 formed in the outside surface of end supports 86 and 88. Thus, the closure means 102 may be pivotally mounted between end supports 86 and 88 by means of pivot pins 112 which are inserted in slots 114 and rest in areas 116 of those slots. When in position in slots 114, the pivot pins 112 allow the closure means 102 to pivot in an arc with its center at area 1 16, thereby allowing the door 104 to pivot into and out of the flow control area 118 immediately adjacent the apertures 110 on the interior of tray 84, as shown in FIGS. 3 and 4. p

The closure means 102 is operably associated with an abutment means 120 as shown in FIGS. 3 through 6. As shown therein, the abutment means 120 comprises a stop lever 122 which is pivotally mounted on the outside of end support 86 by means of a securing means or screw 124 having a bearing surface 126 formed thereon. Stop lever 122 includes a plurality of notches 128 which, when the lever 122 is rotated under the end member 106, contacts and abuts corner 107 of member 106 such that the door 104 only partially covers apertures 100 in tray 84. Thus, by selecting one of the notches 128, or none of the notches and pivoting the lever 122 away from closure means 102 such that the lever rests on foot 123, the closure means 102 may be selectively supported in a position which fully uncovers, partially covers or fully closes all of the apertures 100 in tray 84 to control flow of viscous fluid or emulsion 24 therethrough.

Tray 84 also includes a coating thickness control means 130 which extends the entire length of the tray beneath and slightly behind the apertures 100. Coating thickness control means 130 comprises a spreading bar 131 rigidly secured in a position normal to the under surface of tray 84 as shown in FIGS. 4, 5, 8 and 9. Bar 131 includes a plurality of spaced teeth or projections 132 along the length of the bar. The lower ends of these projections contact the layer of material 16 to be coated as the tray is drawn thereover. Teeth 132 alternate with spaces or apertures 133 which allow a controlled amount of the viscous fluid or emulsion 24 flowing down from apertures 100 to pass therethrough, while pushing the excess ahead of the bar. The fluid that passes spreads in a controlled, predetermined thickness, depending on the height of spaces 133. The height of these spaces is adjustable with elongated gate 134 which is mounted on the back or rear of spreading bar 131 by means of screws 135 inserted throughelongated slots 137. Bar 134 may thus be raised or lowered to determine the thickness of the fluid flowing through by adjusting screws 135 in slots 137. Teeth 132, which contact screen 16, have rounded or arcuate crosssections which smoothly pass along the screen in a comb-like effect without tearing or injuring the screen surface. As the tray is moved over the screen, fluid or emulsion may collect andbuild up in area 139 (FIG. 9) between the .front of the tray and the front surface of spreading bar 131, but will be evenly spread over the screen as it passes through apertures 133.

The tray means is supported by base means 82 without direct physical contact therebetween during the actual coating operation, by means of a series of wheels and rollers cooperating through the flexible material of screen 116 as shown in FIGS. 3 through 6. The base means 82 comprises tray supports and 92 rotationally supporting an alignment rod 96 therebetween beneath the screen 16. Alignment rod 96 is rotationally supported between supports 90 and 92 by means of slotted blocks 136 secured to the inner surfaces of the supports 90 and 92. Alignment rod 96 is disposed in slots 138 of slotted blocks 136 such that it momentarily displaces localized portions of screen 16 vertically upwards and aligns it with coating thickness control means along the entire length of elongated tray 84. Rod 96 thus provides a first reference position, i.e., position A in FIGS. 4 and 6, for this portion of the screen and thereby assures that the screen 16 will always be in contact with the teeth 132 on bar 131. Consequently, the distance or spacing X will be maintained constantly and uniformly along the entire length of tray 84, Le,

across the width of the screen. Without the support of rod 96, large screens would tend to sag, especially from the downward pressure imposed on the screen by bar 131.

The actual support for tray means 80 on base means 82 is provided'by rolling or bearing means or four wheels 140 disposed in pairs on trays supports 90 and 92 directly beneath cooperating wheels 142 mounted on end supports 86 and 88. Additionally, the rolling or bearing means includes wheels 144 mounted on the interior sides of end supports 86 and 88 such that theycooperate with the alignment rod 96 to further support the forward section of the tray meanss 80. The center line of wheels 142 is offset approximately halfway between the center lines of wheels 140 such that each wheel 142 is rotationally supported in the depression 146 between wheels 140 on either end of the tray. The center line of wheels 144, however, is offset slightly forward of the center line of alignment rod 96 as shown in FIG. 6. Thus, wheels 144 are supported by the surface of the alignment rod 96 slightly forward of the vertical plane including the center line of alignment rod 96. This forms the first reference position (Position A) for this position of the screen, as noted above. A second reference position, Position B in FIGS. 4 and 6, is provided by wheels 142 and the forwardmost of wheels 140, i.e., wheels 140 which are closest to alignment rod 96. Reference Position B thus provides a reference line running across the entire width of the spreading means 20. The uniform support of screen 16 between Positions A and B thus assures the planar support of that area of the screen in a plane which is in constant contact with bar 131, a uniform distance X below bar 134 and slightly above the normal position of said screen in framework 18. The combination of the two noted references thereby achieves exactly controlled positioning of the screen relative to the emulsion spreading element 130.

As shown in FIG. 3, wheels 142 are spaced outwardly from end supports 86 and 88 by spacers 143 such that wheels 142 will be in direct vertical alignment with support wheels 140. Similarly, wheels 144 are spaced inwardly by spacers 145 such that they will be in the proper alignment with rod 96. Therefore, the tray means 80 is stably supported by base means 82 with the material or screen to be coated 16 passing therebetween such that the tray means 80 and base means 82 are spaced vertically apart and out of direct contact with one another by the thickness of the screen'ormaterial 16 to be coated.

Movement of the base means 82 under the screen or material 16 is imparted to the supported tray means 80 without-any direct physical contact between these elements. This-is done by means of magnetic coupling or retention means or magnets 150 secured in tray supports 90 and 92 as shown in FIGS. 3 and and cooperative magnetically responsive components on the tray means. Specifically, magnets 150 are disposed within tray supports 90 and 92 and are positioned by spacer blocks 1'51 and 152, as shown in FIG. 3. More than one magnet may be mounted in supports 90 and 92 for ad- I ditional magnetic attraction, if desired. Since, in the preferred embodiment, the majority of the structure of I both the tray means and base means is fabricated from aluminum, which is not a ferro-magnetic material, a section of soft iron 154 may be secured to the underside of each of the end supports 86 and 88 directly over the area of the tray supports 90 and 92 in which the magnets 150 are secured. Thus, the magnetic attraction of the magnet 150 for the soft iron sections 154 will create amagnetic field and circuit to cause the base means 82 and tray means 80 to move in unison along the screen or material 16. Since the tray means 80 is supported by wheels 142 and 144 over the screen or material 16 and moved by means of magnetic attraction, no injury, i.e., ripping or tearing of the screen or material 16 to be coated results.

Each of the tray supports 90 and 92 is adjustable in two directions by means of a rod member 156 and a block member 158 (FIG. 2) and securing means operably associated respectively with both. The block member 158 allows each of the tray supports to slide laterally along the length of the support bar 94. The rod member 156 (FIGS. 4 and 5) allows the vertical adjustment of each of the tray supports with respect to the block members 158. Therefore, the tray supports 90 and'92 may be adjusted laterally, i.e., transverse to the direction of motion of the spreading means 20 as a whole, to accommodate various lengths of tray means 80 and alignment rod 96. Thus, various sized printed I screens or layers of material 16 to be coated may be accommodated by the adjustable spreading means 20.

Referring again to FIGS. 1 and 2, along with FIG. 7,

the means for moving the adjustable spreading means will be described in greater detail. As depicted therein,

the housing 40 houses a motive power means comprising a reversible electric motor 160, a pulley and cable means 170, and electrical control circuitry 178 therefor. The electric motor 160 rotates shafts 162 and 164 on either side thereof, which shafts in turn drive cables 172 and 174. Cables 172 and 174 in turn are mounted about guide pulleys 176 which are rotationally secured to the inside of frame base members 36 and 38. The support bar 94 of base means 82 is slidably mounted on frame base members 36 and 38 such that it may slide the entire length thereof between the adjustable side members or rails 44 and 46. The support bar 94 is fixedly attached to the top portion of cables 172 and 174 such that, when motor 160 drives shafts 162 and 164, cables 172 and 174 will in turn drive support bar 94 in unison therewith. The control circuit 178 for motor 160 includes a push button on-off switch 180 and a rheostat 182 to control the speed of the electric motor. Thus, the motive power means for moving the adjustable spreading means 20 provides a means for automatically moving the associated tray means and base means, and 82, along the length of the material or screen 16 to be coated at a predetermined and controlled rate determined by the rheostat 182. Thus an even and accurate thickness of viscous fluid or emulsion v24 may be applied thereto.

The method of operating the coating apparatus and combined curing means will now be set forth. A framework 18 including a printing screen 16 tautly stretched thereon is secured on adjustable side members or rails 44 and 46 by means of clamping means 60. The adjustable spreading means 20 is positioned at the farthest extremity of the printing screen 16 away from housing 40 by means of the reversible motor 160 and pulley and cable means 170. A quantity of viscous fluid or photographic emulsion 24 is poured into the interior of tray 84. Next the closure means 102 is adjusted for a predetermined rate of flow through apertures by means of the stop lever 122 including notches 128. The start button 180 is then depressed initiating the automatic and controlled movement of the tray means 80 and base means 82 toward the opposite end of the framework 18 adjacent housing 40. The tray means 80 is movably supported by the cooperation of the alignment rod 96 and support wheels and wheels 142 and 144 through the flexible screen 16, and is moved by the magnetic attraction of magnets for soft iron sections 154. The electrical control circuitry 178 may include micro or electrical contact switches (not shown) which automatically stop the motor when the spreading means 20 has reached the proximity of housing40. Since the coating thickness control means 130 is disposed on the housing side of the tray means 80, the tray means 80 is pulled towards the housing 40 in I order to evenly spread the flow of emulsion flowing through apertures 100 downwardly and in front of control means 130. The result is a smooth, even, automatically applied and accurately controlled thickness of emulsion or viscous fluid 24 having a predetermined dimension X (FIGS. 4, 8 and 9) as governed by the distance of bar 134 from the upper surface of the printing screen or material 16 to be coated. After the coating is dryed or baked in the associated curing means 12, the framework 18 may be inverted and coated on the opposite side following steps similar to those described above, if desired.

The curing means 12 used in combination with the coating apparatus described above, is utilized by opening the hinge closure 72 and withdrawing the rollout rack 76. The coated printing screen 16 on framework 18 is then placed on the adjustable roll-out rack 76 and pushed into the interior of the housing 70 of curing means 12. The layer of emulsion or viscous fluid 24 may then be cured, dried or baked on the printing screen or layer of material 16 by the thermostatically controlled ventilation and heating means (not shown) which control the atmospheric conditions within the housing 70.

It will thus be understood that the above described invention effectuates application of controlled, even, exact thickness coatings of photographic emulsions or other viscous fluids to printing screens or other flexible material repeatedly, without requiring special operator skill. It is adaptable to coat varying thicknesses of such fluids on varying sizes and thicknesses of printing screens, and on either side of the screens.

While one preferred form of the invention has been shown and described, other forms differing in details from the preferred form may be apparent to those skilled in the art. Therefore, it will be understood that the embodiment shown in the drawings and described above is merely for illustrative purposes, and is not intended to limit the scope of the invention which is defined by the claims which follow.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combination a support means for supporting a suspended layer of material to be coated, spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material, said spreading means including a tray including a plurality of apertures extending along an edge of said tray positioned adjacent said layer for dispensing said viscous fluid therethrough and onto said layer, a spreader bar including a plurality of spaced teeth projecting therefrom and means adjustably mounting said spreader bar to said tray adjacent and downstream from said apertures such that said teeth project toward said layer a predetermined selectable distance therefrom for controlling the thickness of said viscous fluid applied to said layer, and means for moving said spreading means relative to said support means.

2. A coating apparatus as described in claim 1 wherein said support means comprises a frame, said frame being adjustable in three dimensions for accommodating varying sized frameworks upon which layers of material to be coated are suspended.

3. A coating apparatus as described in claim 2 wherein said frame includes a frame base and at least one adjustable side member slidably mounted thereon, and at least one adjustable clamping means for securely holding said frameworks on said support means, said side member being adapted to slide transversely of the direction of movement of said spreading means along said layer.

4. A coating apparatus as described in claim 3 wherein said adjustable clamping means comprises a cantilevered bar mounted on a spring biased rod, said rod in turn secured to a retaining bearing block in said side member, said rod biasing said bar into contact with 'said framework at all times, said block being slidably adjustable along the length of said side member.

5. A coating apparatus as defined in claim 1 wherein said adjustable spreading means includes base means for movably supporting said tray, said base means movably supporting said tray over said layer without being in physical contact with said tray, said tray and base means cooperating to support successive portions of said material in said precisely controlled planar relationship.

6. A coating apparatus as described in claim 5 wherein said tray includes adjustable closure means adapted to control the flow of said viscous fluid from said tray through said apertures.

7. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combination a support; means for supporting a suspended layer of material to be coated, spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material, said spreading means comprising an elongated tray having a U-shaped cross section and a bottom surface and wherein said tray is mounted between a pair of end supports with said bottom surface at an angle with said layer, said tray including a plurality of apertures formed along the corner of said U-shaped tray closest to said layer such that fluid flows therethrough when said apertures are open, closure means adapted to control the flow of said viscous fluid from said tray through said apertures, coating thickness control means for holding and spreading said viscous fluid, said control means mounted adjacent and between said bottom surface of said tray and said layer such that said flow of fluid through said apertures is spread evenly over said layer by said control means, and a base means for movably supporting said tray, said base means movably supporting said tray over said layer without being in physical contact with said tray, said tray and base means cooperating to support successive portions of said material in said precisely controlled planar relationship.

8. A coating apparatus as described in claim 7 wherein said coating thickness control means comprises a spreading bar rigidly secured under the entire width of said tray; said bar including a plurality of spaced uniform teeth having rounded crosssections and constantly contacting 'said successive portions of said material.

9. A coating apparatus as described in claim 8 wherein said coating thickness control means is adjustable and further includes a control bar adjustably secured to said spreading bar such that the distance between said control bar and said layer of material determines the thickness of said viscous fluid applied to said material and is variable whereby said thickness is predeterminable.

10. A coating apparatus as described in claim 7 wherein said closure means comprises a removable door and an abutment means, said door being pivotally mounted between said end supports such that it may be maintained selectively in a plurality of positions immediately adjacent said aperture by said abutment means thereby selectively covering partially covering or fully uncovering said aperture.

11. A coating apparatus as described in claim wherein said abutment means comprises a stop lever, said lever being pivotally mounted on one of said end supports adjacent said pivotal door and including at least one notch such that said lever may be pivoted into the pivotal path of travel of said door in order to support said door by means of said notch, the position of said notch on said lever thereby governing the amount said aperture is covered by said door.

12. A coating apparatus as described in claim 7 wherein said tray further includes a bearing means comprising at least two wheels mounted on each of said end supports such that said wheels cooperate with said base means in order to support said tray thereon adjacent said layer, said layer passing betwen said wheels mounted on said tray and said base means.-

13. A coating apparatus as described in claim 12 wherein one of said wheels is rotationally supported by a rotational alignment rod on said base means, said one wheels and saidalignment rod cooperating to provide a first supporting reference position for said material,

' and the other of said wheels is rotationally supported other wheel and one of said support wheels cooperating to provide a second supporting reference position for said material; said first and second reference positions supporting saidmaterial in said controlled planar relationship therebetween, the plane of said material being slightly vertically displaced from the normal position of said layer of material as supported on said apparatus and being in constant contact with said coating thickness control means, said wheels, support wheels and alignment rod being spaced respectively from one another by said layer of material.

14. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combinationa support means for supporting a suspended layer of material to be coated, spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material wherein said spreading means includes at least two members, the first of said members being movably supported above said layer of material by the second of said members, said second member positioned below said first member and said layer such that said first member is supported without direct, phsyical contactwith said second member, said spreading means further including magnetic retention means between said first and second members such that said members may be moved together along said layer in unison, and means for moving said spreading means relative to said support means.

15. A coating apparatus as described in claim 1 wherein said means for moving said spreading means comprises a motive power means for movement of said spreading means along said layer at a controlled rate.

substantial portion of the length of said tray.

g 17. The apparatus in claim 16 wherein said tray includes adjustable gate means to controllably vary the opening of said apertures.

18. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combination a support means for supporting a suspended layer of material to be coated wherein said support means comprises a frame, said frame being adjustablein three dimensions for accommodating varying sized frameworks upon which layers of material to be coated are suspended, adjustable spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material wherein said adjustable spreading means comprises a tray means for holding and spreading said viscous fluid and a base means for movably supporting said tray means wherein said tray means comprises an elongated tray mounted between a pair of end supports, an adjustable closure means, a bearing means, and a coating thickness control means, said tray including at least one aperture, said closure means adapted to control the flow of said viscous fluid from said tray through said aperture, and wherein said base means comprises a pair of tray supports, an alignment rod, and a support bar, each of said supports being adjustably mounted on said support bar by means of a rod member and block member, said alignment rod being rotationally and removably mounted between said tray supports adjacent said layer such that it contacts and aligns said layer with said tray means, said support bar being movably mounted on said support-means and connected to said means for moving said spreading means such that said support bar is moved thereby, said base means movably support said tray means over said layer without being in physical contact with said tray means, said tray and base means cooperating to support successive portions of said material in a precisely controlled planar relationship to said tray means, and means for moving said spreading means relative to said support means.

19. A coating apparatus as described in claim 18 wherein each of said tray supports further includes a magnet and a pair of support wheels, said support .wheels in each of said pairs being mounted adjacent one another on horizontally offset axes, and said tray means includes a section of soft iron and at least four wheels rotationally mounted on the ends thereof, two of said wheels on said tray means cooperating with and being supported by said alignment rod, said two wheels being mounted on an axis which is horizontally and vertically offset from the axis of said alignment rod, said two wheels cooperating with said alignment rod to provide a first supporting reference position for said layer of material, the remaining two of said wheels cooperating with and being supported by said pairs of support wheels, said remaining two wheels having an axis horizontally and vertically offset from the axes of said support wheels, said remaining two wheels cooperating with at least two of said support wheels to provide a second supporting reference position for said layer of material, said first and second reference positions supvporting said material in a plane therebetween, said plane being slightly vertically displaced from the normal position of said layer as supported on said apparatus and being in constant contact with said portion of said tray means, said wheels, support wheels and alignment rod being spaced respectively from one another, and thereby being maintained out of direct contact with one another, by said layer, said magnet and soft iron being arranged to attract one another such that said tray means is moved along said layer by said base means 20. A coating apparatus as described in claim 19 in combination with a curing means for selectively drying and baking said coating of viscous fluid on said layer of material, said curing means including a housing, a housing closure means, means for supporting said layer of material within said housing, and means for controlling the atmospheric conditions within said housing.

21. The combination as described in claim 20 wherein said means for supporting said layer of material within said housing comprises at least one roll-out rack which is adjustable to accommodate various sizes of layers of material.

22. An adjustable spreading means for coating a layer of deflectable material mounted in a frame with viscous fluids and adapted to be moved along said layer, said spreading means comprising in combination a tray means for holding and spreading said viscous fluid, and means for movably supporting said tray means over said layer, and means for supporting successive portions of said layer on a side opposite said tray means in controlled planar relationship to at least one portion of said tray means as said tray means is moved along said layer such that the coating of the fluid being applied to said layer has a uniform, predetermined thickness.

23. An adjustable spreading means as described in claim 22 wherein said tray means comprises an elongated tray mounted between a pair of end supports, an adjustable closure means, a bearing means, and a coating thickness control means, said tray including at least one aperture, said closure means adapted to control the flow of said viscous fluid from said tray through said aperture.

24. An adjustable spreading means for coating a layer of suspended material with viscous fluids and adapted to be moved along said layer, said spreading means comprising in combination an elongated tray mounted between a pair of end supports for holding and spreading said viscous fluid and a base means for movably supporting said tray wherein said tray has a U-shaped cross section and a bottom surface, is mounted with the bottom of said U at an angle with said layer, and includes a plurality of apertures, said apertures being formed along the corner of said U-shaped tray closest to said layer such that fluid flows therethrough when said apertures are open, said base means movably supporting said tray means over said layer without said base means being in physical contact with said tray means, said tray and base means cooperating to support successive portions of said layer in a precisely controlled planar relationship to at least one portion of said tray means as said spreading means is moved along said layer, an adjustable closure means, a bearing means, and a coating thickness control means, said control means mounted adjacent and between said bottom surface of said tray and said layer such that the fluid that flows through said apertures is spread evenly over said layer by said control means such that the coating of the fluid being applied to said layer has a uniform, predetermined, exact thickness.

25. An adjustable spreading means as described in claim 24 wherein said coating thickness control means comprises a spreading bar rigidly secured under the entire width of said tray; said bar including a plurality of spaced uniform teeth having rounded cross-sections and constantly contacting said successive portions of said material.

26. A coating apparatus as described in claim 25 wherein said coating thickness control means is adjust able and further includes a control bar adjustably secured to said spreading bar such that the distance between said control bar and said layer of material determines the thickness of said viscous fluid applied to said material and is variable whereby said thickness is predeterminable.

27. An adjustable spreading means as described in claim 25 wherein said closure means comprises a removable door and an abutment means, said door being pivotally mounted between said end supports such that it may be maintained selectively in a plurality of positions immediately adjacent said aperture by said abutment means thereby selectively covering, partially covering or fully uncovering said aperture.

28. An adjustable spreading means as described in claim 27 wherein said abutment means comprises a stop lever, said lever being pivotally mounted on one of said end supports adjacent said pivotal door and including at least one notch such that said lever may be pivoted into the pivotal path of travel of said door in order to support said door by means of said notch, the position of said notch on said lever thereby governing the amount said aperture is covered by said door.

29. An adjustable spreading means as described in claim 24 wherein said bearing means comprise at least two wheels mounted on each of said end supports such that said wheels cooperate with said base means in order to support said tray thereon adjacent said layer with said layer passing between said wheels and tray and said base means, said layer being supported in said planar relationship with respect to said coating thickness control means.

30. An adjustable spreading means as described in claim 29 wherein one of said wheels is rotationally supported by a rotational alignment rod on said base means, and the other of said wheels is rotationally supported by a pair of support wheels on said base means, said wheels, support wheels and alignment bar being spaced respectively from one another by said layer, said one wheel and said alignment rod defining a first supporting reference position for said layer, said other wheel and at least one of said support wheels defining a second supporting reference position for said layer, said planar relationship comprising said layer supported between said first and second reference positions in a plane slightly vertically displaced from the normal position of said layer as supported on said apparatus and being in constant contact with said coating thickness control means such that the thickness of the coating applied is precisely determined.

31. An adjustable spreading means as described in claim 30 wherein said end supports each include a section of soft iron and said base means includes a magnet, said magnet and soft iron section being arranged adjacent one another such that movement of said base means imparts a corresponding movement of said tray.

32. Apparatus for coating stencil screens withviscous fluids such as photographic emulsions comprising in combination a coating means including a spreading member and a supporting member, said members cooperating to temporarily support successive portions of said screen in a plane parallel to and in constant contact with said spreading member as said successive portions are coated with said fluid, said spreading member spreading a uniform predetermined thickness of said fluid on said successive portions, rolling means for separating said members, said rolling means interacting with said screen, magnetic means coupling said members through said screen such that they move in unison along said screen.

33. The apparatus defined in claim 22 wherein said means for supporting said layer comprises a roller, means for mounting said roller in alignment with said tray, and means for moving said roller along said layer in cooperation with said tray.

34. A coating apparatus for the application of a viscous fluid to a stencil screen tautly stretched over a frame, said apparatus comprising means for supporting said stencil screen, an elongated reservoir for viscous fluid to be applied to said screen, said reservoir including a plurality of spaced apertures therealong through which the viscous fluid passes, means for selectively restricting said apertures to control the flow rate of viscous fluid therethrough, a spreader bar movably mounted to said reservoir and including an edge adapted to engage the fluid applied from said reservoir to evenly spread the fluid onto said screen, said spreader bar being adjustable toward and away from said screen to control the thickness of the coating applied by said coating apparatus, and means mounting said reservoir in position relative to said screen to permit flow of fluid through said apertures in said reservoir onto said screen and for moving said reservoir across the surface of said screen to apply a coating thereon.

35. The apparatus as defined in claim 34 wherein said support means is positioned to engage said screen on the side opposite said reservoir and is movable in cooperation with said reservoir to support said screen immediately adjacent said reservoir as said reservoir travels across the surface of the screen.

36. The apparatus as defined in claim 35 wherein said support means comprises a roller having a cylindrical surface which engages said screen and rotates therealong as said roller is drawn across the surface of said screen opposite said reservoir. 

1. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combination a support means for supporting a suspended layer of material to be coated, spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material, said spreading means including a tray including a plurality of apertures extending along an edge of said tray positioned adjacent said layer for dispensing said viscous fluid therethrough and onto said layer, a spreader bar including a plurality of spaced teeth projecting therefrom and means adjustably mounting said spreader bar to said tray adjacent and downstream from said apertures such that said teeth project toward said layer a predetermined selectable distance therefrom for controlling the thickness of said viscous fluid applied to said layer, and means for moving said spreading means relative to said support means.
 2. A coating apparatus as described in claim 1 wherein said support means comprises a frame, said frame being adjustable in three dimensions for accommodating varying sized frameworks upon which layers of material to be coated are suspended.
 3. A coating apparatus as described in claim 2 wherein said frame includes a frame base and at least one adjustable side member slidably mounted thereon, and at least one adjustable clamping means for securely holding said frameworks on said support means, said side member being adapted to slide transversely of the directioN of movement of said spreading means along said layer.
 4. A coating apparatus as described in claim 3 wherein said adjustable clamping means comprises a cantilevered bar mounted on a spring biased rod, said rod in turn secured to a retaining bearing block in said side member, said rod biasing said bar into contact with said framework at all times, said block being slidably adjustable along the length of said side member.
 5. A coating apparatus as defined in claim 1 wherein said adjustable spreading means includes base means for movably supporting said tray, said base means movably supporting said tray over said layer without being in physical contact with said tray, said tray and base means cooperating to support successive portions of said material in said precisely controlled planar relationship.
 6. A coating apparatus as described in claim 5 wherein said tray includes adjustable closure means adapted to control the flow of said viscous fluid from said tray through said apertures.
 7. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combination a support means for supporting a suspended layer of material to be coated, spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material, said spreading means comprising an elongated tray having a U-shaped cross section and a bottom surface and wherein said tray is mounted between a pair of end supports with said bottom surface at an angle with said layer, said tray including a plurality of apertures formed along the corner of said U-shaped tray closest to said layer such that fluid flows therethrough when said apertures are open, closure means adapted to control the flow of said viscous fluid from said tray through said apertures, coating thickness control means for holding and spreading said viscous fluid, said control means mounted adjacent and between said bottom surface of said tray and said layer such that said flow of fluid through said apertures is spread evenly over said layer by said control means, and a base means for movably supporting said tray, said base means movably supporting said tray over said layer without being in physical contact with said tray, said tray and base means cooperating to support successive portions of said material in said precisely controlled planar relationship.
 8. A coating apparatus as described in claim 7 wherein said coating thickness control means comprises a spreading bar rigidly secured under the entire width of said tray; said bar including a plurality of spaced uniform teeth having rounded cross-sections and constantly contacting said successive portions of said material.
 9. A coating apparatus as described in claim 8 wherein said coating thickness control means is adjustable and further includes a control bar adjustably secured to said spreading bar such that the distance between said control bar and said layer of material determines the thickness of said viscous fluid applied to said material and is variable whereby said thickness is predeterminable.
 10. A coating apparatus as described in claim 7 wherein said closure means comprises a removable door and an abutment means, said door being pivotally mounted between said end supports such that it may be maintained selectively in a plurality of positions immediately adjacent said aperture by said abutment means thereby selectively covering partially covering or fully uncovering said aperture.
 11. A coating apparatus as described in claim 10 wherein said abutment means comprises a stop lever, said lever being pivotally mounted on one of said end supports adjacent said pivotal door and including at least one notch such that said lever may be pivoted into the pivotal path of travel of said door in order to support said door by means Of said notch, the position of said notch on said lever thereby governing the amount said aperture is covered by said door.
 12. A coating apparatus as described in claim 7 wherein said tray further includes a bearing means comprising at least two wheels mounted on each of said end supports such that said wheels cooperate with said base means in order to support said tray thereon adjacent said layer, said layer passing betwen said wheels mounted on said tray and said base means.
 13. A coating apparatus as described in claim 12 wherein one of said wheels is rotationally supported by a rotational alignment rod on said base means, said one wheels and said alignment rod cooperating to provide a first supporting reference position for said material, and the other of said wheels is rotationally supported by a pair of support wheels on said base means, said other wheel and one of said support wheels cooperating to provide a second supporting reference position for said material; said first and second reference positions supporting said material in said controlled planar relationship therebetween, the plane of said material being slightly vertically displaced from the normal position of said layer of material as supported on said apparatus and being in constant contact with said coating thickness control means, said wheels, support wheels and alignment rod being spaced respectively from one another by said layer of material.
 14. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combination a support means for supporting a suspended layer of material to be coated, spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material wherein said spreading means includes at least two members, the first of said members being movably supported above said layer of material by the second of said members, said second member positioned below said first member and said layer such that said first member is supported without direct, phsyical contact with said second member, said spreading means further including magnetic retention means between said first and second members such that said members may be moved together along said layer in unison, and means for moving said spreading means relative to said support means.
 15. A coating apparatus as described in claim 1 wherein said means for moving said spreading means comprises a motive power means for movement of said spreading means along said layer at a controlled rate.
 16. The coating apparatus in claim 1 wherein said teeth engage said material portions in said planar relationship, with said teeth being evenly spaced along a substantial portion of the length of said tray.
 17. The apparatus in claim 16 wherein said tray includes adjustable gate means to controllably vary the opening of said apertures.
 18. A coating apparatus for the application of viscous fluids to a taut, flexible, suspended layer of material such as a stencil screen comprising in combination a support means for supporting a suspended layer of material to be coated wherein said support means comprises a frame, said frame being adjustable in three dimensions for accommodating varying sized frameworks upon which layers of material to be coated are suspended, adjustable spreading means for holding a quantity of viscous fluid, temporarily supporting portions of said material in a precisely controlled planar relationship, and automatically spreading controlled amounts of viscous fluid evenly on said layer of material wherein said adjustable spreading means comprises a tray means for holding and spreading said viscous fluid and a base means for movably supporting said tray means wherein said tray means comprises an elongated tray mounted between a pair of end supports, an adjustable closure Means, a bearing means, and a coating thickness control means, said tray including at least one aperture, said closure means adapted to control the flow of said viscous fluid from said tray through said aperture, and wherein said base means comprises a pair of tray supports, an alignment rod, and a support bar, each of said supports being adjustably mounted on said support bar by means of a rod member and block member, said alignment rod being rotationally and removably mounted between said tray supports adjacent said layer such that it contacts and aligns said layer with said tray means, said support bar being movably mounted on said support means and connected to said means for moving said spreading means such that said support bar is moved thereby, said base means movably support said tray means over said layer without being in physical contact with said tray means, said tray and base means cooperating to support successive portions of said material in a precisely controlled planar relationship to said tray means, and means for moving said spreading means relative to said support means.
 19. A coating apparatus as described in claim 18 wherein each of said tray supports further includes a magnet and a pair of support wheels, said support wheels in each of said pairs being mounted adjacent one another on horizontally offset axes, and said tray means includes a section of soft iron and at least four wheels rotationally mounted on the ends thereof, two of said wheels on said tray means cooperating with and being supported by said alignment rod, said two wheels being mounted on an axis which is horizontally and vertically offset from the axis of said alignment rod, said two wheels cooperating with said alignment rod to provide a first supporting reference position for said layer of material, the remaining two of said wheels cooperating with and being supported by said pairs of support wheels, said remaining two wheels having an axis horizontally and vertically offset from the axes of said support wheels, said remaining two wheels cooperating with at least two of said support wheels to provide a second supporting reference position for said layer of material, said first and second reference positions supporting said material in a plane therebetween, said plane being slightly vertically displaced from the normal position of said layer as supported on said apparatus and being in constant contact with said portion of said tray means, said wheels, support wheels and alignment rod being spaced respectively from one another, and thereby being maintained out of direct contact with one another, by said layer, said magnet and soft iron being arranged to attract one another such that said tray means is moved along said layer by said base means.
 20. A coating apparatus as described in claim 19 in combination with a curing means for selectively drying and baking said coating of viscous fluid on said layer of material, said curing means including a housing, a housing closure means, means for supporting said layer of material within said housing, and means for controlling the atmospheric conditions within said housing.
 21. The combination as described in claim 20 wherein said means for supporting said layer of material within said housing comprises at least one roll-out rack which is adjustable to accommodate various sizes of layers of material.
 22. An adjustable spreading means for coating a layer of deflectable material mounted in a frame with viscous fluids and adapted to be moved along said layer, said spreading means comprising in combination a tray means for holding and spreading said viscous fluid, and means for movably supporting said tray means over said layer, and means for supporting successive portions of said layer on a side opposite said tray means in controlled planar relationship to at least one portion of said tray means as said tray means is moved along said layer such that the coating of the fluid being applied to said layer has a uniform, predetermined thickness.
 23. An adjustable spreading means as described in claim 22 wherein said tray means comprises an elongated tray mounted between a pair of end supports, an adjustable closure means, a bearing means, and a coating thickness control means, said tray including at least one aperture, said closure means adapted to control the flow of said viscous fluid from said tray through said aperture.
 24. An adjustable spreading means for coating a layer of suspended material with viscous fluids and adapted to be moved along said layer, said spreading means comprising in combination an elongated tray mounted between a pair of end supports for holding and spreading said viscous fluid and a base means for movably supporting said tray wherein said tray has a U-shaped cross section and a bottom surface, is mounted with the bottom of said U at an angle with said layer, and includes a plurality of apertures, said apertures being formed along the corner of said U-shaped tray closest to said layer such that fluid flows therethrough when said apertures are open, said base means movably supporting said tray means over said layer without said base means being in physical contact with said tray means, said tray and base means cooperating to support successive portions of said layer in a precisely controlled planar relationship to at least one portion of said tray means as said spreading means is moved along said layer, an adjustable closure means, a bearing means, and a coating thickness control means, said control means mounted adjacent and between said bottom surface of said tray and said layer such that the fluid that flows through said apertures is spread evenly over said layer by said control means such that the coating of the fluid being applied to said layer has a uniform, predetermined, exact thickness.
 25. An adjustable spreading means as described in claim 24 wherein said coating thickness control means comprises a spreading bar rigidly secured under the entire width of said tray; said bar including a plurality of spaced uniform teeth having rounded cross-sections and constantly contacting said successive portions of said material.
 26. A coating apparatus as described in claim 25 wherein said coating thickness control means is adjustable and further includes a control bar adjustably secured to said spreading bar such that the distance between said control bar and said layer of material determines the thickness of said viscous fluid applied to said material and is variable whereby said thickness is predeterminable.
 27. An adjustable spreading means as described in claim 25 wherein said closure means comprises a removable door and an abutment means, said door being pivotally mounted between said end supports such that it may be maintained selectively in a plurality of positions immediately adjacent said aperture by said abutment means thereby selectively covering, partially covering or fully uncovering said aperture.
 28. An adjustable spreading means as described in claim 27 wherein said abutment means comprises a stop lever, said lever being pivotally mounted on one of said end supports adjacent said pivotal door and including at least one notch such that said lever may be pivoted into the pivotal path of travel of said door in order to support said door by means of said notch, the position of said notch on said lever thereby governing the amount said aperture is covered by said door.
 29. An adjustable spreading means as described in claim 24 wherein said bearing means comprise at least two wheels mounted on each of said end supports such that said wheels cooperate with said base means in order to support said tray thereon adjacent said layer with said layer passing between said wheels and tray and said base means, said layer being supported in said planar relationship with respect to said coating thickness control means.
 30. An adjustable spreading means as described in claim 29 wherein one of said wheels is rotationally supported by a rotational alignment rod on said Base means, and the other of said wheels is rotationally supported by a pair of support wheels on said base means, said wheels, support wheels and alignment bar being spaced respectively from one another by said layer, said one wheel and said alignment rod defining a first supporting reference position for said layer, said other wheel and at least one of said support wheels defining a second supporting reference position for said layer, said planar relationship comprising said layer supported between said first and second reference positions in a plane slightly vertically displaced from the normal position of said layer as supported on said apparatus and being in constant contact with said coating thickness control means such that the thickness of the coating applied is precisely determined.
 31. An adjustable spreading means as described in claim 30 wherein said end supports each include a section of soft iron and said base means includes a magnet, said magnet and soft iron section being arranged adjacent one another such that movement of said base means imparts a corresponding movement of said tray.
 32. Apparatus for coating stencil screens with viscous fluids such as photographic emulsions comprising in combination a coating means including a spreading member and a supporting member, said members cooperating to temporarily support successive portions of said screen in a plane parallel to and in constant contact with said spreading member as said successive portions are coated with said fluid, said spreading member spreading a uniform predetermined thickness of said fluid on said successive portions, rolling means for separating said members, said rolling means interacting with said screen, magnetic means coupling said members through said screen such that they move in unison along said screen.
 33. The apparatus defined in claim 22 wherein said means for supporting said layer comprises a roller, means for mounting said roller in alignment with said tray, and means for moving said roller along said layer in cooperation with said tray.
 34. A coating apparatus for the application of a viscous fluid to a stencil screen tautly stretched over a frame, said apparatus comprising means for supporting said stencil screen, an elongated reservoir for viscous fluid to be applied to said screen, said reservoir including a plurality of spaced apertures therealong through which the viscous fluid passes, means for selectively restricting said apertures to control the flow rate of viscous fluid therethrough, a spreader bar movably mounted to said reservoir and including an edge adapted to engage the fluid applied from said reservoir to evenly spread the fluid onto said screen, said spreader bar being adjustable toward and away from said screen to control the thickness of the coating applied by said coating apparatus, and means mounting said reservoir in position relative to said screen to permit flow of fluid through said apertures in said reservoir onto said screen and for moving said reservoir across the surface of said screen to apply a coating thereon.
 35. The apparatus as defined in claim 34 wherein said support means is positioned to engage said screen on the side opposite said reservoir and is movable in cooperation with said reservoir to support said screen immediately adjacent said reservoir as said reservoir travels across the surface of the screen.
 36. The apparatus as defined in claim 35 wherein said support means comprises a roller having a cylindrical surface which engages said screen and rotates therealong as said roller is drawn across the surface of said screen opposite said reservoir. 